Spectrum Controls 1756sc-IF8u - Manual (Page 112)

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ControlLogix ™ Universal Analog Input Module
Exposed Junction Thermocouples
As shown in the illustration that follows, using exposed junction
thermocouples may result in removal of channel to channel isolation. This
may occur if multiple exposed thermocouples are in direct contact with
electrically conductive process material. To prevent violation of channel to
channel isolation:
• For multiple exposed thermocouples, do not allow the measuring
junction of the thermocouple to make direct contact with electrically
conductive process material.
• Use a single exposed junction thermocouple with multiple ungrounded
junction thermocouples.
• Use all ungrounded junction thermocouple instead of the exposed
junction type.
+
-
CH3
+
-
CH0
MUXES
1756sc-IF8u
Exposed junction with shielded cable
Conductive Material